In a conventional refrigerator, the freezing compartment and refrigerating compartment generally cannot be operated independently of each other. At times, the overall operation of both the refrigerating compartment and the freezing compartment is not necessary. For example, in a winter season or at other times when the amount of food to be refrigerated is small, the operation of both compartments of the refrigerator causes a waste of electrical power. Recently, new forms of refrigerators have been utilized. For example, when the amount of food to be refrigerated is large, the freezing compartment is capable of being used as a refrigerating compartment thereby allowing the capacity for refrigeration to be increased. In such new refrigerators, however, there have been problems which have made it impossible to maintain the refrigerating temperature at the desired level during certain periods. As with the conventional refrigerators, the new refrigerators also have the disadvantage of wasting electrical power, because both the refrigerating compartment and the freezing compartment are always operated even when the amount of food to be refrigerated is small.